ML20246F622

Concludes That Proposed Insp Plan,W/Exception of Weld 02M-S3,meets Guidelines of Generic Ltr 88-01 & Acceptable. NRC Recommends That Util Ultrasonically Examine Weld 02M-S3

ML20246F622
Person / Time
Site:	Quad Cities
Issue date:	08/23/1989
From:	Ross T Office of Nuclear Reactor Regulation
To:	Kovach T COMMONWEALTH EDISON CO.
References
GL-88-01, GL-88-1, TAC-73421, NUDOCS 8908310085
Download: ML20246F622 (4)

Text

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NUCLEAR REGULATORY COMMISSION E g . wash NGTom,o.c.20sss .

1 y..C.. Y.j f August 23. 1989

. Docket Nos. 50-254.and 50-265 Mr. Thomas'J. Kovach LNucleae 8.icensing Manager-Common a:th Edison Company.

Post OM* ;e Box' 767.-

Chicago, Illinois 60690

Dear Mr. Kovach:

, SL'PJECT: QUAD CITIES, UNIT 1, IGSCC INSPECTION PLAN (TAC NO. 73421)

Reference:

(a) Letter. from R. Stols (Ceco) to Dr. Murley (NRC) dated June 9, 1989.

-(b) Letter from'R. Stols (CECO) to Dr. Murley (NRC) dated July 13, 1989.

/The Nuclear Regulatory Comission (NRC)' staff has reviewed reference (a) from L Commonwealth Edison Company (Ceco) regarding the intergranular stress corrosion.

cracking (IGSCC)inspectionplantobeperformedatQuadCitiesUnit1during the upcoming refueling outage. *ihe staff concludes, with the exception.of-weld 02M-53, that the nroposed inspection plant meets the guidelir.es of Generic

~ Letter 88-01 and .is acceptable.

'During the 1983 refueling outage, Weld 02M-S3 was reinforced with a pipe lock after completion of two-layer overlay repair. Due-to the outage schedule, post-overlay examination was not performed.- In reference visually'itspect.only the pipe lock (of the repaired weld)(a) in lieuCECO proposed to of ultrasonic

. examination of the weldment. Justification for this proposal was provided by-reference (b). However, after subsequent' review, the staff does not agree with CECO's proposal to inspect only the pipe lock for the following reasons:

(1) Justification for inspecting only the pipe lock was supported mainly by an analytical evaluation, showing the presence of favorable stress

. distribution on the pipe joint as a result of pipe lock preload.

Although limited laboratory testing was performed to demonstrate the adequacy of the pipe lock design, testing on intergranular stress corrosion cracked samples to verify the effectiveness of IGSCC mitigation was not performed. l (2) There is very little' field experience in the application of pipe locks.

Therefore, it' is necessary to confirm the effectiveness of the pipe locks in mitigating IGSCC by periodic examination of the weldments. The pipe

. lock assembly should also be inspected after disassembly to ensure there i is no degradation of its components.

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I Hr. Thomas J. Kovach  !

(3) Based on recently reported inspection results, the staff has some concerns regarding the effectiveness of induction heating stress improvement (IHSI) and hydrogen water chemistry (HWC) processes to mitigate IGSCC. In several BWR operating plants, a number of IGSCC susceptible welds were found to contain new flaws after IHSI treatment. This was not expected based on analyticel evaluation and laboratory testing of the IHSI treated. j welds. Dresden Unit 2 is the letd plant in applying hydrogen water '

chemistry. After successful operation with HWC for three fuel cycles, a number of piping welds were found to contain IGSCC flaws in a recent inspection. As a result, the staif has withdrawn the inspection credit {

i for HWC from Dresden Unit 2. These unexpected inspection results have reinforced the need to perform augnented inspection to confirm the effectiveness of IGSCC mitigation nethods. .

(4) In Generic Letter 88-01, the staff recommends that clamping devices (such as pipe locks) may be used for temporary reinforcement of cracked weldments. However,~each such application requires staff review and approval. Furthermore, in NUREG-0313, Revision 2, it is stated that one advantage of clamping devices is that they may be periodically removed for l weld examination. The staff position clearly does not recommend the use '

of clamping devices for long term repair, and requires weld examination if its used for an extended period of time.

Based upon the considerations above, the staff recommends that CECO ultrasonically examine weld 02M-53 during the upcoming or next refueling outage. Furthermore, we request that you provide us within forty-five days a written commitment confirming Ceco's intention to do so, or additional justification to support not doing ultrasonic examination of this weld.

Sincerely, Thierry M. Ross, Project Manager Project Directorate III-2 Division of Reactor Projects - III, IV, V, and Special Projects cc: See next page

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+ + ' August 23, 1989-

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, Mr. ~ Thomas J. - Kovach 1. ,

l .(3) Based on recently reported inspection results, the staff has some' concerns regarding the effectiveness of. induction heating stress improvement (IHSI) and hydrogen water chemistry (HWC) processes to mitigate IGSCC. In several.BWR operating plants, a number of IGSCC susceptible welds were found to contain new flaws after IHSI treatment. This was not expected based on analytical evaluation and laboratory testing of the IHSI treated welds. - Dresden Unit 2 is the lead plant in applying hydrogen water chemistry. After successful operation with HWC for three fuel cycles, a number of piping welds were found to contain IGSCC flaws in a recent inspection. As a result, the staff has withdrawn the inspection credit for HWC from Dresden Unit 2. These unexpected inspection results have reinforced the need to perform' augmented inspection to confirm the effectiveness of IGSCC mitigation methods.

(4) In Generic Letter 88-01, the staff recommends that clamping devices (such as pipe locks) may be used for temporary reinforcement of cracked weldments. .However, each such application requires staff review and

. approval. Furthermore, in NUREG-0313, Revision 2, it is stated that one advantagt of clamping devices is that they may be periodically removed for weld examination. -The staff position clearly does not recommend the use of clamping devices for long term repair, and requires weld examination if its used for an extended period of time.

Based upon the considerations above, the staff recommends that Ceco ultrasonically examine. weld 02M-53 during the upcoming or next refueling outage. Furthermore, we' request that you provide us within forty-five days a written commitment confirming CECO's intention to do so, or additional justification to support =

not doing ultrasonic examination of this weld.

Sincerely, Thierry M. Ross, Project Manager Project Directorate III-2 Division of Reactor Projects - III, IV, V, and Special Projects cc: See next page DISTRIBUTION:

Docket file TRoss ACRS (10)

NRC & Local PDRs MVirgilio 0GC PDIII-2 r/f .EJordan PShemanski LLuther BGrimes PDIII-2 PDIII-2

/.L PDIll-2 TRoss:km LLutheM PShemanski 8/ p /89 8/A3/89 8/y) /89 1 l

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Mr. Thomas'J. Kovach .;

. Quad Cities Nuclear Power Station l

Commonwealth. Edison Company Units 1 and 2

{ 1

.cc:

Mr. Stephen E. Shelton -

Vice President

-Iowa-Illinois Gas and l

Electric Company P. O. Box 4350 Davenport, Iowa 52808 j

Michael I. Miller, Esq.

Sidley and Austin One first National Plaza Chicago, Illinois 60603

-Mr. Richard Bax Station Manager-Quad Cities Nuclear Power Station

-22710 206th Avenue North Cordova, Illinois 61242 Resident Inspector U. S. Nuclear Regulatory Comission 22712 206th Avenue North Cordova,. Illinois 61242

' Chairman Rock Island County Board of Supervisors 1504 3rd Avenue Rock Island County Office Bldg. .

Rock' Island, Illinois 61201 Illinois Department of Nuclear Safety

' Office of Nuclear Facility Safety 1035 Outer Park Drive Springfield, Illinois 62704 Regional Administrator, Region III U. S. Nuclear Regulatory Comission 799 Roosevelt Road, Bldg. f4 Glen Ellyn, Illinois 60137

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